Cover crops are traditionally used to cover bare land to protect the soil and/or improve soil characteristics between cash-crop cycles, or planted alongside the cash-crop. Farmers have used cover crops for a long time, and each different species can benefit a farm in different ways. One of these cover crops used in Florida and Southern USA is Sunn Hemp. Sunn hemp is a commonly use summer cover crop in Florida that is use mostly as green manure and has been proven to help in the control of root-knot nematodes.

Some Characteristics of Sunn Hemp are:

• Is a legume that originates from India.
• It is used to grow fiber, can be used as a forage crop, and as a summer cover crop in the Southern USA.
• Can be planted in hardiness zones 8 – 13 in the southern part of the USA.
• It is propagated by seeds which can be purchased from many seed distributors in South Florida. (Current prices may range approximately from $1.10 – $1.50 / lb)
• Sunn Hemp has a production cycle of 60 – 80 days, the plant can exceed 6 feet in height, and it has yellow flowers.
• It can produce approximately 6 – 8.5 tons of dry biomass per acre.
• Is drought tolerant and can grow in both low pH soils and high pH soils.

Some Benefits of Sunn Hemp are:

• It can reduce weed pressure on the farm.
• It can help reduce soil erosion.
• Has been proven to have a positive effect on controlling root-knot nematodes and other parasitic nematode species.
• Can improve soil organic matter when used as green manure or organic mulch.

How to Use Sunn Hemp?

• Sunn Hemp is mostly used as green manure. It is planted 2 – 3 months before the intended agricultural commodity. It gets mowed and incorporated into the soil in early bloom to use it as fertilizer (green manure). This will help with soil nutrition and nematode control.
• Sunn hemp can also be used as an organic mulch. The cover crop is mowed and left on the soil surface, and it will cause it to slowly release nutrients that could be available to the agricultural commodity that will be planted after this cover crop.
• Sunn Hemp can be used for nematode suppression. Sunn Hemp is not immune to parasitic nematodes, but it has been proven to produce allelopathic compounds that are toxic to several nematode species.

Conclusion

Sunn Hemp could be a good choice for a summer cover crop if you are looking to improve your farm soil nutrition and control root-knot nematodes. Knowing the characteristics of this crop and how to use it could be beneficial to help you improve your farm operation.

For more information about Sunn Hemp and other cover crops, access the following “Ask IFAS” publications:

QUESTIONS AND ANSWERS FOR USING SUNN HEMP (CROTALARIA JUNCEA L.) AS A GREEN MANURE COVER CROP

MANAGEMENT OF NEMATODES AND SOIL FERTILITY WITH SUNN HEMP COVER CROP

COVER CROPS FOR MANAGING ROOT-KNOT NEMATODES

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